software punk
TRANSCRIPT
Software Punk
Lior Bar-On, 2016
Controversial ideas in Software Development That just might work.
Source: songpop.wikia.com
Who is this Guy? (Lior Bar-On)
בלוג ארכיטקטורת תוכנה
Developer
Architect
Chief ArchitectBlogger
Inheritance & OOSource: schedule.sxsw.com
Inheritance is a bold violation of OO Principles!
1. Encapsulation (“הכמסה”)2. PolyMorphism (“ריבוי-צורות”)3. Inheritance (“הורשה”)
Violation
Flawed Inheritance Code Example
Composition > Inheritance
“... our second principle of object-oriented design:
Favor object composition over class inheritance.
”
Source: http://slidedeck.io/parnurzeal/why-opensource-slides Source: Addison wesley
A moment of Skepticism...
while (condition_always_true) { // do something ...}
Inheritance as tool for (poor?) abstractions
Inheritance as tool for (poor?) abstractions
Inheritance as tool for (poor?) abstractions
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Inheritance as tool for (poor?) abstractions
Inheritance as tool for (poor?) abstractions
?
Inheritance as tool for (poor?) abstractions
?
Inheritance as tool for (poor?) abstractions
?
Inheritance as tool for (poor?) abstractions
Black Cab → A, B, C, D
Yellow Cab → A, E, F
Green Cab → A, B, D, E
Scooter → C, E, G
PHV → B, C, F
Inheritance breaking our reading flow
?
?
Recap
Inheritance can cause “unexpected behavior” - but it is rare.
Inheritance (“is-a” delegation) is too limited to expressed real world domain objects. Use Inheritance only with dead-simple cases.
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2
In some programming languages, Inheritance makes the code less expressive.3
Bad, bad Abstractions
D.R.Y Happiness!
DRY = Don’t Repeat YourselfSource: dreamstime
D.R.Y Happiness @Gett-API
HTTP Retry: The POST case
...IDEMPOTENT_METHODS = [“GET”, “PUT”]if method in IDEMPOTENT_METHODS { // http request retry}...
HTTP Retry: The POST case #2
...if can_retry { if _err == CONNECTION_ERROR { // http request retry }} ...
The Safe Methods case
...if method == “GET” { // use cache}...
The Safe Methods Case #2 - POST (reading)
...if is_cacheable { // use cache}...
Cache TTL settings
...// some logic with cache times......
The Fallback cache Case
...if _err == CONNECTION_ERROR { // try to load response from fallback cache}...
Not very DRY, but simpler!
Code Duplication is mushrooming
The non-visible dependencies of that system...
Recap
Not only code Rots. Abstractions Rot too.It’s okay to occasionally favor Code Duplications and avoid non-meaningful abstraction.
When an Abstraction rots: Stop. do a reverse, and return the code duplication.
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2
You Spend too much on Unit Tests
There are several ways to achievehigh quality....
Source: profiles.com.sg
Type A: Codename “Lisa” (a Unit Test)
Source: a presentation by Lior Bar-On
Type A: Codename “Lisa” (a Unit Test)
Source: a presentation by Lior Bar-On
Isolated unit test
Type B Codename “Bart”
Source: a presentation by Lior Bar-On
Type B Codename “Bart”
Source: a presentation by Lior Bar-On
Unit-Integration Test
Integration Test
Type B Codename “Bart”
Source: a presentation by Lior Bar-On
Example: Aggregating 11 model methods into a single test
Type C - Codename “Cat In The Hat”
Source: marocdeserttours.wordpress.com
Type C - Codename “Cat In The Hat”
Great Production Monitoring /w Continuous Deployment
Type C - Codename “Cat In The Hat”
Source: marocdeserttours.wordpress.com
Ideal Target: when covering 90%+ of the cases is not possible - or just too expensive
Recap
Unit Tests is great - but it has its costs.It fit perfectly for logical code units (if / for)
Integration / Unit-Integration tests are more broad - but more cost efficient.
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2Sometimes, it worth monitoring things only on production.When done well - it can be cheap, otherwise - very expensive.
3
Don’t take things for granted